56064 Federal Register / Vol. 71, No. 186 / Tuesday, September 26, 2006 / Proposed Rules 

Applicability 

(c) This AD applies to EMBRAER Model 

ERJ 170–100 LR, –100 STD, –100 SE, and 

–100 SU airplanes, certificated in any 

category; serial numbers 17000007, 

17000033, 17000034, 17000036 through 

17000046 inclusive, and 17000050 through 

17000067 inclusive. 

Unsafe Condition 

(d) This AD results from failure of an 

electrical bonding clamp, used to attach the 

electrical bonding straps to the fuel system 

lines. We are issuing this AD to prevent loss 

of bonding protection in the interior of the 

fuel tanks or adjacent areas that, in 

combination with lightning strike, could 

result in a fuel tank explosion and 

consequent loss of the airplane. 

Compliance 

(e) You are responsible for having the 

actions required by this AD performed within 

the compliance times specified, unless the 

actions have already been done. 

Replacement 

(f) Within 5,000 flight hours after the 

effective date of this AD: Replace all 

electrical bonding clamps having part 

number AN735D4 or AN735D6 with new 

clamps and replace the attaching hardware 

with new or serviceable attaching hardware, 

and do the other specified action, by 

accomplishing all of the actions specified in 

the Accomplishment Instructions of 

EMBRAER Service Bulletin 170–28–0009, 

Revision 01, dated February 23, 2006. The 

other specified action must be done before 

further flight. 

Credit for Previous Service Bulletin 

(g) Actions done before the effective date 

of this AD in accordance with EMBRAER 

Service Bulletin 170–28–0009, dated 

December 30, 2005, are acceptable for 

compliance with the requirements of 

paragraph (f) of this AD. 

Alternative Methods of Compliance 

(AMOCs) 

(h)(1) The Manager, International Branch, 

ANM–116, Transport Airplane Directorate, 

FAA, has the authority to approve AMOCs 

for this AD, if requested in accordance with 

the procedures found in 14 CFR 39.19. 

(2) Before using any AMOC approved in 

accordance with § 39.19 on any airplane to 

which the AMOC applies, notify the 

appropriate principal inspector in the FAA 

Flight Standards Certificate Holding District 

Office. 

Related Information 

(i) Brazilian airworthiness directive 2006–

06–03, effective July 7, 2006, also addresses 

the subject of this AD. 

Issued in Renton, Washington, on 

September 14, 2006. 

Kalene C. Yanamura, 

Acting Manager, Transport Airplane 

Directorate, Aircraft Certification Service. 

[FR Doc. 06–8225 Filed 9–25–06; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2004–19755; Directorate 

Identifier 2004–NM–23–AD] 

RIN 2120–AA64 

Airworthiness Directives; Boeing 

Model 747 Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), Department of 

Transportation (DOT). 

ACTION: Supplemental notice of 

proposed rulemaking (NPRM); 

reopening of comment period. 

SUMMARY: The FAA is revising an earlier 

proposed airworthiness directive (AD) 

for certain Boeing Model 747 airplanes. 

The original NPRM would have 

required repetitive tests to detect hot air 

leaking from the trim air diffuser ducts 

or sidewall riser duct assemblies 

(collectively referred to in this proposed 

AD as ‘‘TADDs’’), related investigative 

actions, and corrective actions if 

necessary. The original NPRM also 

would have provided an optional 

terminating action for the repetitive 

tests. The original NPRM resulted from 

reports of sealant deteriorating on the 

outside of the center wing fuel tank and 

analysis that sealant may deteriorate 

inside the tank due to excess heat from 

leaking TADDs. This action revises the 

original NPRM by referring to improved 

inspection procedures and extending 

the repetitive interval for certain related 

investigative actions. We are proposing 

this supplemental NPRM to prevent 

leakage of fuel or fuel vapors into areas 

where ignition sources may be present, 

which could result in a fire or 

explosion. 

DATES: We must receive comments on 

this supplemental NPRM by October 23, 

2006. 

ADDRESSES: Use one of the following 

addresses to submit comments on this 

supplemental NPRM. 

• DOT Docket Web site: Go to http:// 

dms.dot.gov and follow the instructions 

for sending your comments 

electronically. 

• Government-wide rulemaking Web 

site: Go to http://www.regulations.gov 

and follow the instructions for sending 

your comments electronically. 

• Mail: Docket Management Facility; 

U.S. Department of Transportation, 400 

Seventh Street, SW., Nassif Building, 

Room PL–401, Washington, DC 20590. 

• Fax: (202) 493–2251. 

• Hand Delivery: Room PL–401 on 

the plaza level of the Nassif Building, 

400 Seventh Street, SW., Washington, 

DC, between 9 a.m. and 5 p.m., Monday 

through Friday, except Federal holidays. 

Contact Boeing Commercial 

Airplanes, P.O. Box 3707, Seattle, 

Washington 98124–2207, for service 

information identified in this proposed 

AD. 

FOR FURTHER INFORMATION CONTACT: Dan 

Kinney, Aerospace Engineer, Propulsion 

Branch, ANM–140S, FAA, Seattle 

Aircraft Certification Office, 1601 Lind 

Avenue, SW., Renton, Washington 

98057–3356; telephone (425) 917–6499; 

fax (425) 917–6590. 

SUPPLEMENTARY INFORMATION: 

Comments Invited 

We invite you to submit any relevant 

written data, views, or arguments 

regarding this supplemental NPRM. 

Send your comments to an address 

listed in the ADDRESSES section. Include 

the docket number ‘‘Docket No. FAA–

2004–19755; Directorate Identifier 

2004–NM–23–AD’’ at the beginning of 

your comments. We specifically invite 

comments on the overall regulatory, 

economic, environmental, and energy 

aspects of this supplemental NPRM. We 

will consider all comments received by 

the closing date and may amend this 

supplemental NPRM in light of those 

comments. 

We will post all comments submitted, 

without change, to http://dms.dot.gov, 

including any personal information you 

provide. We will also post a report 

summarizing each substantive verbal 

contact with FAA personnel concerning 

this supplemental NPRM. Using the 

search function of that Web site, anyone 

can find and read the comments in any 

of our dockets, including the name of 

the individual who sent the comment 

(or signed the comment on behalf of an 

association, business, labor union, etc.). 

You may review the DOT’s complete 

Privacy Act Statement in the Federal 

Register published on April 11, 2000 

(65 FR 19477–78), or you may visit 

http://dms.dot.gov. 

Examining the Docket 

You may examine the AD docket on 

the Internet at http://dms.dot.gov, or in 

person at the Docket Management 

Facility office between 9 a.m. and 5 

p.m., Monday through Friday, except 

Federal holidays. The Docket 

Management Facility office (telephone 

(800) 647–5227) is located on the plaza 

level in the Nassif Building at the DOT 

street address stated in ADDRESSES. 

Comments will be available in the AD 

docket shortly after the Docket 

Management System receives them. 


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Discussion 

We proposed to amend 14 CFR part 

39 with a notice of proposed rulemaking 

(NPRM) for an AD (the ‘‘original 

NPRM’’) for certain Boeing Model 747 

airplanes. The original NPRM was 

published in the Federal Register on 

December 1, 2004 (69 FR 69844). The 

original NPRM proposed to require 

repetitive tests to detect hot air leaking 

from the trim air diffuser ducts or 

sidewall riser duct assemblies 

(collectively referred to in this 

supplemental NPRM as ‘‘TADDs’’), 

related investigative actions, and 

corrective actions if necessary. The 

original NPRM also would have 

provided an optional terminating action 

for the repetitive tests. 

Actions Since Original NPRM Was 

Issued 

Since we issued the original NPRM, 

we have received reports indicating that 

the procedures referenced in Boeing 

Alert Service Bulletin 747–21A2418, 

Revision 2, dated March 4, 2004 (which 

we referenced in the original NPRM as 

the applicable source of service 

information for the proposed actions), 

are not sufficient to detect a damaged 

TADD in a timely manner. 

Relevant Service Information 

We have reviewed Boeing Service 

Bulletin 747–21A2418, Revision 4, 

dated November 17, 2005. Revision 4 of 

the service bulletin describes 

procedures that are similar to those in 

Revision 2. However, Revision 4 revises 

the part numbers for certain improved 

sidewall riser duct assemblies for 

installation on Boeing Model 747–400 

series airplanes that are not freighters. 

This change is due to new 

environmental and flammabilityresistance standards required under 

amendments 25–110, 91–279, 121–301, 

125–43, and 135–90 of the Federal 

Aviation Regulations. (Refer to the final 

rule, docket no. FAA–2000–7909, 

‘‘Improved Flammability Standards for 

Thermal/Acoustic Insulation Materials 

Used in Transport Category Airplanes’’

(68 FR 45046, July 31, 2003; with 

corrections published 68 FR 50054, 

August 20, 2003; and 69 FR 6532, 

February 11, 2004).) Revision 4 of the 

service bulletin also recommends 

increasing the initial inspection 

threshold from 27,000 flight hours to 

32,000 flight hours, and the repetitive 

inspection interval from 7,000 flight 

hours to 12,000 flight hours, for the 

general visual inspection for damage or 

discrepancies of the TADDs. 

Certain changes to the service 

information that were originally 

introduced in Boeing Service Bulletin 

747–21A2418, Revision 3, dated 

December 21, 2004, are retained in 

Revision 4 of the service bulletin: 

• Chapter 21–61–20 of the airplane 

maintenance manual (AMM) has been 

revised to contain more definitive pass/ 

fail criteria for the repetitive tests and 

inspections of the TADDs. These revised 

criteria increase the chances of a 

defective TADD being detected in a 

timely manner. 

• Chapter 21–61–21 of the AMM 

contains procedures for unwrapping 

insulation blankets as necessary before 

the general visual inspection to detect 

defective TADDs is done on Boeing 

Model 747–400 non-freighter series 

airplanes. 

Accomplishing the actions specified 

in Revision 4 of the service information 

is intended to adequately address the 

unsafe condition. We have revised 

paragraphs (f), (g), (h), and (j) and Note 

2 of this supplemental NPRM to refer to 

Revision 4 of the service information. 

We have also added a new paragraph (k) 

to this supplemental NPRM, and reidentified the subsequent paragraph, to 

give credit for actions done before the 

effective date of the AD in accordance 

with previous issues of the service 

bulletin. 

With regard to extending compliance 

times for the general visual inspection, 

we have revised Table 1 of this 

supplemental NPRM to extend the 

repetitive interval for the general visual 

inspections from 7,000 flight hours to 

12,000 flight hours. We have also 

revised Table 1 of this supplemental 

NPRM to extend the initial compliance 

threshold from 27,000 total flight hours 

to 32,000 total flight hours. 

Comments 

We have considered the following 

comments on the original NPRM. 

Request To Relieve Testing 

Requirement 

British Airways requests that we 

revise paragraph (f) of the original 

NPRM to relieve operators of the 

requirement to do a test to detect hot air 

leaking from the TADDs at the same 

time as the general visual inspection for 

damage or discrepancies of the TADDs. 

The commenter notes that, if the 

inspection is being accomplished, there 

is no need to do the test during the same 

maintenance check. The commenter 

assumes that the inspection exceeds the 

intent of the test in that the inspection 

would detect discrepancies of the 

TADDs that the test may not. 

We concur with the commenter’s 

request. We agree that it would be 

redundant to perform a hot air leak test 

at the same time as the general visual 

inspection when the repetitive intervals 

for these actions coincide. Therefore, we 

have revised paragraph (f) of this 

supplemental NPRM to clarify that, 

when the compliance times for a hot air 

leak test and a general visual inspection 

coincide, the hot air leak test is not 

required at that time. 

Request To Allow Installation of 

Serviceable Improved TADDs 

The Air Transport Association (ATA), 

on behalf of its member Northwest 

Airlines (NWA), and Boeing request that 

we revise paragraphs (h) and (j) and 

Note 3 of the original NPRM to allow 

installation of serviceable improved 

TADDs. Boeing states that the improved 

TADDs are expected to hold up well in 

service, and its customers are concerned 

about the proposed restriction on 

installing serviceable TADDs. In its 

comment submitted through ATA, NWA 

states that it does not believe that the 

failure rate of new TADDs is a 

significant improvement over properly 

repaired or serviceable used TADDs. 

NWA states that only a very small 

percentage of high-time TADDS have 

failed in service, and it believes that all 

duct leaks will be sufficiently addressed 

by the repetitive tests and inspections 

proposed in the original NPRM. NWA 

also disagrees that the TADDs 

deteriorate at a known rate in service, 

which was the justification stated in the 

original NPRM for not allowing 

installation of used TADDs. Similarly, 

Boeing comments that the deterioration 

rate is highly variable. 

We agree with the commenters’

request to allow installing serviceable 

improved TADDs. Our intent was to 

prohibit installing used ducts of the old 

type, not used ducts of the improved 

type. We have determined that 

installing serviceable improved parts 

will provide an acceptable level of 

safety. We have revised paragraphs (h) 

and (j) of this supplemental NPRM 

accordingly, and we have omitted Note 

3 from this supplemental NPRM. 

However, as mentioned in the 

discussion of New Relevant Service 

Information, improved flammability 

standards may prohibit installing 

certain new, improved TADDs on nonfreighter airplanes. Subsequent to the 

publication of the original NPRM, some 

of the improved TADDs failed a test of 

their insulation that is required by the 

improved flammability standards. Thus, 

under the requirements of that rule, 

certain improved TADDs that were 

listed in revisions of Boeing Service 

Bulletin 747–21A2418 prior to Revision 

4, can no longer be installed (although 

they need not be removed if they were 


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installed prior to September 2, 2003, the 

effective date of FAA–2000–7909). 

Also, we do not agree with the 

commenters’ statements that the rate of 

deterioration is unknown, although we 

acknowledge that there are many 

variables that contribute to the 

deterioration of the TADDs. The rate of 

deterioration is known to the extent that 

we know that TADDs having 

accumulated more than 20,000 total 

flight hours are suspect. Also, we do not 

know of an inspection process that 

would be adequate to ensure the 

integrity of a used duct of the old 

material. For these reasons, we have 

determined that it is not appropriate to 

allow installation of used TADDs made 

of the old material. 

Request To Remove References to 

Deteriorated Sealant 

Boeing requests that we revise the 

original NPRM to remove references to 

‘‘reports of deteriorating sealants both 

inside and outside the center wing fuel 

tank due to heat damage from leaking 

TADDs.’’ Boeing states that it is not 

aware of reports of damaged fuel tanks 

caused by leaking TADDs. 

We agree to revise the statement of 

what prompted the proposed AD to 

remove the references to reports of 

deterioration of the sealant inside the 

center wing fuel tank. We are unable to 

confirm direct observation of primary 

seal deterioration. 

However, we disagree that primary or 

secondary seal deterioration is unlikely. 

Following reports of TADD leaks, 

Boeing analyzed the temperatures that 

the primary (inside) and secondary 

(outside) fuel barriers could reach. 

Analysis revealed that the secondary 

barrier could reach temperatures 

between 300 °F and 450 °F, and that 

internal tank temperatures could reach 

378 °F. The sealants are not effective 

above 325 °F and are not qualified for 

prolonged exposure above 160 °F. In 

addition, FAA personnel observed 

deterioration of the secondary sealant in 

the center wing fuel tank. Therefore, if 

any damage or discrepancy of a TADD 

is found, we find it necessary to require 

a general visual inspection for damage 

of the primary and secondary fuel 

barriers of the center wing tank, and 

adjacent areas and items, as specified in 

paragraph (h) of this supplemental 

NPRM. 

Based on this information, we have 

revised the Summary of this 

supplemental NPRM to state that the 

original NPRM ‘‘resulted from reports of 

sealant deteriorating on the outside of 

the center wing fuel tank and analysis 

that sealant may deteriorate inside the 

tank due to excess heat from leaking 

TADDs.’’ We have similarly revised 

paragraph (d) of this supplemental 

NPRM. 

Request To Require Inspections Only 

on Affected Side 

ATA, on behalf of NWA, requests that 

we revise paragraph (h) of the original 

NPRM to require an inspection for 

damage of the fuel barriers and adjacent 

areas only on the side of the airplane 

where a TADD failed. In its comment 

submitted through ATA, NWA states 

that the original NPRM does not 

acknowledge that the TADDs are located 

on both the left and right sides of the 

airplane. Neither ATA nor NWA state a 

justification for the request. 

We infer that the commenter’s request 

is intended to reduce the amount of 

work that needs to be accomplished to 

allow a quicker return of the airplane to 

service. We agree that it would be 

acceptable to inspect the fuel barriers 

and adjacent areas only on the side of 

the airplane where a TADD failed if no 

damage is found on the side of the 

airplane where a TADD failed. However, 

if any damage of the fuel barriers or 

adjacent areas is found on the side of 

the airplane where a TADD failed, both 

sides of the airplane must be inspected. 

Both sides must be inspected because 

the barrier damage is caused by hot air 

and if there is damage to one side, then 

there may be enough leakage to damage 

the other side. 

We have revised paragraph (h)(1) of 

this AD to state that, ‘‘If no damage is 

found on the side of the airplane where 

the damaged or discrepant TADD is 

found, inspecting the other side of the 

airplane is not required.’’

In addition, we have revised 

paragraph (j) of this AD to clarify the 

specific circumstances under which 

tests and inspections required by 

paragraph (f) of this AD are terminated. 

These changes better acknowledge that, 

as the commenter points out, there are 

TADDs on both the left and right sides 

of the airplane. 

Request To Revise Repetitive Inspection 

Intervals 

KLM Royal Dutch Airlines (KLM) 

requests that we extend the repetitive 

interval for the hot air leak test specified 

in paragraph (f)(1) of the original NPRM 

from 1,200 flight hours to 1,600 flight 

hours. The commenter states that the 

repetitive interval of 1,200 flight hours 

is not consistent with its maintenance 

intervals. KLM explains that its A-check 

is 770 flight hours, so it would have to 

perform this test either every A-check or 

in between A-checks. KLM states that 

either alternative would result in 

excessive cost. KLM notes that a 

repetitive interval of 1,600 flight hours 

would allow it to perform the test every 

second A-check. Boeing also 

commented that the interval for the hot 

air leak test should coincide with actual 

A-check intervals. 

We do not agree with the request to 

extend the repetitive interval for the hot 

air leak test. The extension of the 

repetitive interval for the general visual 

inspections to 12,000 flight hours, as 

discussed previously, is contingent on 

the repetitive hot air leak tests being 

performed at intervals not to exceed 

1,200 flight hours. We find that this 

repetitive interval is necessary to ensure 

that any discrepant TADD will be 

detected in a timely manner. We note 

that the 1,200-flight-hour repetitive 

interval is consistent with Boeing’s 

recommendation in Revision 4 of the 

service bulletin and in its re-evaluation 

of compliance times. Further, since 

maintenance schedules vary among 

operators, it is not possible for us to 

revise the repetitive interval to meet the 

needs of a specific operator. In 

developing an appropriate repetitive 

interval for this action, we considered 

the manufacturer’s recommendation, the 

degree of urgency associated with the 

subject unsafe condition, the average 

utilization of the affected fleet, and the 

time necessary to perform the test 

(estimated at 3 work hours). In light of 

all of these factors, we find that 1,200 

flight hours is an appropriate interval of 

time for affected airplanes to continue to 

operate between repetitive tests without 

compromising safety. We have not 

changed the supplemental NPRM in this 

regard. However, paragraph (l) of the 

supplemental NPRM provides operators 

the opportunity to request an extension 

of the compliance time if data are 

presented to justify such an extension. 

Request To Revise Compliance Time for 

Inspection of Replaced TADDs 

ATA, on behalf of NWA, suggests that 

we revise the compliance time for the 

general visual inspection for damaged or 

replaced TADDs made of the original 

material. Paragraph (i) of the original 

NPRM specifies a compliance time of 

27,000 flight hours after the TADD is 

replaced for this inspection. The 

commenter suggests that this 

compliance time be revised to ‘‘the next 

C-check after 21,200 flight hours.’’

We partially agree with this request. 

We do not agree with the request to state 

the compliance time in relation to a Ccheck. We find that such a non-specific 

compliance time would not ensure that 

damaged TADDs are detected in a 

timely manner. However, we agree to 

extend the compliance time for 

inspecting replaced TADDs from 27,000 


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flight hours to 32,000 flight hours after 

replacement. We note that affected 

operators may elect to do the general 

visual inspection of the TADDs earlier 

than the stated compliance time, if it is 

more convenient to their maintenance 

schedules. We have revised paragraph 

(i) of this supplemental NPRM 

accordingly. 

Request To Revise Compliance Time for 

Initial Leak Test 

ATA, on behalf of NWA, requests that 

we revise the compliance time for the 

initial test specified in paragraph (f)(1) 

of the original NPRM. NWA states 

support for the test but believes that an 

equivalent level of safety can be 

achieved by doing the initial test at the 

compliance time specified in the 

referenced service bulletin, which the 

commenter interprets as 180 days or 

2,000 hours, whichever is first. NWA 

states that a failed duct is often detected 

when floorboards or sidewalls become 

hot, or when the airplane crew has 

difficulty controlling cabin 

temperatures. Thus, a failed duct is 

often corrected by normal maintenance 

practices that limit exposure to high 

temperatures. For this reason, NWA 

states that compliance time for the 

initial inspection recommended in the 

service bulletin is sufficient to detect 

duct leaks that are not detected during 

normal operations. 

We do not agree with the commenter’s 

request. We note that 180 days or 2,000 

flight hours (whichever is first) is the 

compliance time recommended by the 

referenced service bulletin for airplanes 

with 20,000 or more total flight hours. 

However, as we explained in the 

‘‘Differences Between the Proposed AD 

and Service Information’’ section of the 

original NPRM, the compliance 

threshold of 21,200 total flight hours is 

the equivalent of the inspection 

threshold of 20,000 total flight hours 

specified in the service bulletin, plus 

one repeat interval (1,200 flight hours). 

In addition, the manufacturer has not 

requested that we revise the compliance 

time proposed in the original NPRM. In 

developing an appropriate compliance 

time for the initial test, we considered 

the manufacturer’s recommendation, 

and the degree of urgency associated 

with the subject unsafe condition. In 

light of these factors, we find that the 

compliance time of 21,200 total flight 

hours, or 1,200 flight hours after the 

effective date of the AD, whichever is 

later, represents an appropriate interval 

of time for affected airplanes to continue 

to operate without compromising safety. 

We have not changed the supplemental 

NPRM in this regard. 

Request To Ensure Adequate Supply of 

Replacement Parts 

Lufthansa requests that we ensure that 

an adequate supply of replacement parts 

will be available for operators to comply 

with the proposed requirements. The 

commenter notes that there have been 

delays in obtaining material for planned 

modifications in accordance with 

Boeing Service Bulletin 747–21A2418. 

The commenter states that it anticipates 

that it will find TADDs that must be 

replaced. 

We acknowledge the commenter’s 

concerns and the delays it experienced. 

Parts availability is one of the factors 

that we consider when establishing a 

compliance time for an AD. In this case, 

we have determined through the 

manufacturer that an adequate supply of 

replacement parts will be available for 

operators to accomplish the proposed 

requirements within the proposed 

compliance time. We find that no 

additional changes to the supplemental 

NPRM are needed in this regard. 

Request To Clarify Requirements of 

Paragraph (h) 

Boeing requests that we revise 

paragraph (h) of the original NPRM to 

state that the actions in that paragraph 

apply if any discrepancy is found 

during either the hot air leak test or the 

general visual inspection for damage in 

accordance with paragraph (f) of the 

original NPRM. 

We contacted Boeing for clarification 

of the meaning and intent of its 

comment. Upon further review of 

paragraph (h) of the original NPRM, 

Boeing concluded its comment was not 

necessary and could be withdrawn. We 

have not changed the supplemental 

NPRM in this regard. 

Request To Allow Use of Later 

Revisions of Service Information 

Air New Zealand (ANZ) requests that 

we revise paragraph (j) of the original 

NPRM, Optional Terminating Action, to 

allow use of later revisions of the 

referenced service information. ANZ 

notes that, when the AD refers to a 

specific revision of the service bulletin, 

e.g., Revision 2, operators may not use 

the later revisions without being out of 

compliance with the requirements of the 

AD when new service information is 

released that contains new part numbers 

for equivalent or better parts. ANZ 

suggests that we include language 

referring to ‘‘any subsequent documents, 

which list a new or equivalent part 

number or better, that does not have this 

unsafe condition.’’

We do not agree with the request to 

refer to later revisions of the service 

information that have not yet been 

released. (As explained previously, we 

have revised this supplemental NPRM 

to refer to Boeing Service Bulletin 747–

21A2418, Revision 4.) When we refer to 

a specific service bulletin in an AD, 

using a phrase such as that suggested by 

the commenter, or a phrase like ‘‘or later 

FAA-approved revisions,’’ violates 

Office of the Federal Register 

regulations for approving materials that 

are incorporated by reference. However, 

affected operators may request approval 

to use a later revision of the referenced 

service bulletin as an alternative method 

of compliance, under the provisions of 

paragraph (l) of this supplemental 

NPRM. We have not changed the 

supplemental NPRM further in this 

regard. 

Request To Revise Cost Impact 

Qantas Airways (QANTAS) requests 

that we revise the cost impact stated in 

the original NPRM. The commenter 

believes that the original NPRM 

underestimates the number of work 

hours necessary to do the general visual 

inspection for damage or discrepancies 

of the TADDs. QANTAS notes that 

significant time is necessary to gain 

access to the TADDs to perform the 

inspection and to close up after the 

inspection, in addition to testing the inseat entertainment equipment. The 

commenter notes that the estimate of 43 

work hours in Boeing Service Bulletin 

747–21A2418 is more realistic. 

We do not agree. The cost analysis in 

AD rulemaking actions typically does 

not include incidental costs such as the 

time required to gain access and close 

up, time necessary for planning, or time 

necessitated by other administrative 

actions. Those incidental costs, which 

may vary significantly among operators, 

are almost impossible to calculate. We 

have not changed the supplemental 

NPRM in this regard. 

Requests for Editorial Changes 

Boeing requests that we revise the 

Relevant Service Information section of 

the original NPRM as follows: 

• Revise the statement, ‘‘The related 

investigative actions are repetitive 

general visual inspections for 

discrepancies or damage of the 

TADDs* * * ’’ to also refer to the hot air 

leak tests as related investigative 

actions. 

• Revise the statement, ‘‘After a 

TADD is replaced with a new, improved 

TADD, the repetitive inspections are no 

longer needed for that TADD,’’ to note 

that neither the repetitive leak tests nor 

the repetitive inspections are needed 

after a new, improved TADD is 

installed. 


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Boeing’s rationale for the first change 

is that the statement in the original 

NPRM implies that only the visual 

inspections constitute valid 

investigative actions. Boeing’s rationale 

for the second change is to avoid 

questions (from operators) and 

misinterpretation. 

We acknowledge the commenter’s 

requests. However, we do not agree that 

any change is necessary. The Relevant 

Service Information section of the 

original NPRM states that the referenced 

service bulletin ‘‘describes procedures 

for repetitive tests to detect hot air 

leaking from the TADDs, related 

investigative actions, and corrective 

actions if necessary.’’ The statement to 

which the commenter refers defines 

what we mean by ‘‘related investigative 

actions.’’ We find that the contents of 

the Relevant Service Information section 

are sufficiently clear as written in the 

original NPRM. With regard to the 

commenter’s second item, we agree with 

the statement as revised by the 

commenter. However, the Relevant 

Service Information section of the 

original NPRM is not restated in this 

supplemental NPRM. Thus, no change 

is possible in this regard. 

Explanation of Additional Changes 

We have reduced the estimated 

number of airplanes that would be 

affected by this supplemental NPRM to 

be consistent with the number of 

airplanes identified in the service 

bulletin. 

After the original NPRM was issued, 

we reviewed the figures we have used 

over the past several years to calculate 

AD costs to operators. To account for 

various inflationary costs in the airline 

industry, we find it necessary to 

increase the labor rate used in these 

calculations from $65 per work hour to 

$80 per work hour. The cost impact 

information, below, reflects this 

increase in the specified hourly labor 

rate. 

We have revised this action to clarify 

the appropriate procedure for notifying 

the principal inspector before using any 

approved AMOC on any airplane to 

which the AMOC applies. 

FAA’s Determination and Proposed 

Requirements of the Supplemental 

NPRM 

Certain changes discussed above 

expand the scope of the original NPRM; 

therefore, we have determined that it is 

necessary to reopen the comment period 

to provide additional opportunity for 

public comment on this supplemental 

NPRM. 

Costs of Compliance 

There are about 1,081 airplanes of the 

affected design in the worldwide fleet. 

The following table provides the 

estimated costs for U.S. operators to 

comply with this supplemental NPRM. 

ESTIMATED COSTS

Action Work 

hours 

Average 

labor rate per 

hour 

Cost per airplane 

Number 

of U.S.- 

registered 

airplanes 

Fleet cost 

Hot air leak test ........................................ 3 $80 $240, per test cycle ................................. 216 $51,840, per 

test cycle. 

General visual inspection ......................... 5 80 400, per inspection cycle ......................... 216 86,400, per inspection 

cycle. 

Authority for This Rulemaking 

Title 49 of the United States Code 

specifies the FAA’s authority to issue 

rules on aviation safety. Subtitle I, 

Section 106, describes the authority of 

the FAA Administrator. Subtitle VII, 

Aviation Programs, describes in more 

detail the scope of the Agency’s 

authority. 

We are issuing this rulemaking under 

the authority described in Subtitle VII, 

Part A, Subpart III, Section 44701, 

‘‘General requirements.’’ Under that 

section, Congress charges the FAA with 

promoting safe flight of civil aircraft in 

air commerce by prescribing regulations 

for practices, methods, and procedures 

the Administrator finds necessary for 

safety in air commerce. This regulation 

is within the scope of that authority 

because it addresses an unsafe condition 

that is likely to exist or develop on 

products identified in this rulemaking 

action. 

Regulatory Findings 

We have determined that this 

proposed AD would not have federalism 

implications under Executive Order 

13132. This proposed AD would not 

have a substantial direct effect on the 

States, on the relationship between the 

national Government and the States, or 

on the distribution of power and 

responsibilities among the various 

levels of government. 

For the reasons discussed above, I 

certify that the proposed regulation: 

1. Is not a ‘‘significant regulatory 

action’’ under Executive Order 12866; 

2. Is not a ‘‘significant rule’’ under the 

DOT Regulatory Policies and Procedures 

(44 FR 11034, February 26, 1979); and 

3. Will not have a significant 

economic impact, positive or negative, 

on a substantial number of small entities 

under the criteria of the Regulatory 

Flexibility Act. 

We prepared a regulatory evaluation 

of the estimated costs to comply with 

this supplemental NPRM and placed it 

in the AD docket. See the ADDRESSES

section for a location to examine the 

regulatory evaluation. 

List of Subjects in 14 CFR Part 39 

Air transportation, Aircraft, Aviation 

safety, Safety. 

The Proposed Amendment 

Accordingly, under the authority 

delegated to me by the Administrator, 

the FAA proposes to amend 14 CFR part 

39 as follows: 

PART 39—AIRWORTHINESS 

DIRECTIVES 

1. The authority citation for part 39 

continues to read as follows: 

Authority: 49 U.S.C. 106(g), 40113, 44701. 

§ 39.13 [Amended] 

2. The Federal Aviation 

Administration (FAA) amends § 39.13 

by adding the following new 

airworthiness directive (AD): 

Boeing: Docket No. FAA–2004–19755; 

Directorate Identifier 2004–NM–23–AD. 

Comments Due Date 

(a) The FAA must receive comments on 

this AD action by October 23, 2006. 

Affected ADs 

(b) None. 

Applicability 

(c) This AD applies to Boeing Model 747–

100, 747–100B, 747–100B SUD, 747–200B, 


sroberts on PROD1PC70 with PROPOSALS
Federal Register / Vol. 71, No. 186 / Tuesday, September 26, 2006 / Proposed Rules 56069 

747–200C, 747–200F, 747–300, 747–400, 

747–400D, 747–400F, 747SR, and 747SP 

series airplanes; certificated in any category; 

line numbers 1 through 1316 inclusive. 

Unsafe Condition 

(d) This AD results from reports of sealant 

deteriorating on the outside of the center 

wing fuel tank and analysis that sealant may 

deteriorate inside the tank due to excess heat 

from leaking trim air diffuser ducts or 

sidewall riser duct assemblies (collectively 

referred to in this AD as ‘‘TADDs’’). We are 

issuing this AD to prevent leakage of fuel or 

fuel vapors into areas where ignition sources 

may be present, which could result in a fire 

or explosion. 

Compliance 

(e) You are responsible for having the 

actions required by this AD performed within 

the compliance times specified, unless the 

actions have already been done. 

Repetitive Tests and Inspections 

(f) Do the actions in Table 1 of this AD at 

the times specified in Table 1 of this AD, in 

accordance with the Accomplishment 

Instructions of Boeing Service Bulletin 747–

21A2418, Revision 4, dated November 17, 

2005. When the compliance times for a hot 

air leak test and a general visual inspection 

coincide, the hot air leak test is not required 

at that time, but is required within 1,200 

flight hours (i.e., one repeat interval) after the 

general visual inspection. 

TABLE 1.—COMPLIANCE TIMES

Do this action— Initially at the later of—

Then repeat within 

this interval until paragraph (j) is done—

(1) Repetitive test to detect hot air leaking from TADDs ...... Prior to the accumulation of 21,200 total flight hours, or 

within 1,200 flight hours after the effective date of this 

AD.

1,200 flight hours. 

(2) General visual inspection for damage or discrepancies 

of the TADDs.

Prior to the accumulation of 32,000 total flight hours, or 

within 12,000 flight hours after the effective date of this 

AD, except as provided by paragraph (g) of this AD.

12,000 flight hours. 

Note 1: For the purposes of this AD, a 

general visual inspection is: ‘‘A visual 

examination of an interior or exterior area, 

installation, or assembly to detect obvious 

damage, failure, or irregularity. This level of 

inspection is made from within touching 

distance unless otherwise specified. A mirror 

may be necessary to ensure visual access to 

all surfaces in the inspection area. This level 

of inspection is made under normally 

available lighting conditions such as 

daylight, hangar lighting, flashlight, or 

droplight and may require removal or 

opening of access panels or doors. Stands, 

ladders, or platforms may be required to gain 

proximity to the area being checked.’’

Note 2: Boeing Service Bulletin 747–

21A2418, Revision 4, refers to Chapters 21–

61–20 and 21–61–21 of the 747 Airplane 

Maintenance Manual as an additional source 

for service information for the test and 

inspections of the TADDs. 

(g) If any hot air leak is found during any 

test required by paragraph (f) of this AD: 

Before further flight, do the general visual 

inspection for damage or discrepancies of the 

TADDs, in accordance with the 

Accomplishment Instructions of Boeing 

Service Bulletin 747–21A2418, Revision 4, 

dated November 17, 2005. 

Corrective Actions 

(h) If any damage or discrepancy is found 

during any general visual inspection for 

damage required by paragraph (f) or (g) of 

this AD: Do the actions in paragraphs (h)(1), 

(h)(2), (h)(3), and (h)(4) of this AD, as 

applicable. Do all of these actions in 

accordance with the Accomplishment 

Instructions of Boeing Service Bulletin 747–

21A2418, Revision 4, dated November 17, 

2005. 

(1) Before further flight: Perform a general 

visual inspection for damage of the primary 

and secondary fuel barriers of the center 

wing tank; structure adjacent to the 

discrepant TADD; and cables, cable pulleys, 

and raised cable seals in the over-wing area. 

If no damage is found on the side of the 

airplane where the damaged or discrepant 

TADD is found, inspecting the other side of 

the airplane is not required. 

(2) Before further flight: Repair all damage 

or discrepancies found. 

(3) Before further flight: Replace any 

damaged TADD with a new TADD having the 

same part number or a new or serviceable, 

improved TADD having a part number listed 

in the ‘‘New TADD Part Number’’ or ‘‘New 

Sidewall Riser Duct Assy Part Number’’

column, as applicable, of the tables in 

Section 2.C.2. of the service bulletin. 

(4) Repeat the test and inspection required 

by paragraph (f) of this AD at the times 

specified in Table 1 of this AD, except as 

provided by paragraphs (i) and (j) of this AD. 

(i) For any original-material TADD that is 

replaced with a new TADD having the same 

part number as the TADD being replaced: 

Within 21,200 flight hours after the TADD is 

replaced, do the test to detect hot air leaking 

from the replaced TADD, and within 32,000 

flight hours after the TADD is replaced, do 

the general visual inspection for damage, as 

specified in paragraph (f) of this AD. 

Thereafter, repeat the test and inspection at 

the repetitive intervals specified in Table 1 

of this AD, except when the times for a hot 

air leak test and a general visual inspection 

coincide, the leak test is not required. 

Optional Terminating Action 

(j) Replacing existing TADDs with new or 

serviceable, improved TADDs terminates 

repetitive test and inspection requirements as 

specified in paragraphs (j)(1), (j)(2), and (j)(3) 

of this AD. New or serviceable, improved 

TADDs are those having a part number listed 

in the ‘‘New TADD Part Number’’ or ‘‘New 

Sidewall Riser Duct Assy Part Number’’

column, as applicable, of the tables in 

Section 2.C.2. of Boeing Service Bulletin 

747–21A2418, Revision 3, dated December 

21, 2004; or Revision 4, dated November 17, 

2005. 

(1) The repetitive general visual 

inspections required by paragraph (f)(2) of 

this AD are terminated for each TADD that 

is replaced with a new or serviceable, 

improved TADD. 

(2) Replacing all TADDs on one side of the 

airplane with new or serviceable, improved 

TADDs terminates all repetitive tests 

required by paragraph (f)(1) of this AD and 

all repetitive inspections required by 

paragraph (f)(2) of this AD only for the side 

of the airplane on which the improved 

TADDs are installed. 

(3) Replacing all TADDs on both sides of 

the airplane with new or serviceable, 

improved TADDs terminates all repetitive 

tests required by paragraph (f)(1) of this AD 

and all repetitive inspections required by 

paragraph (f)(2) of this AD. 

Previously Accomplished Actions 

(k) Actions done before the effective date 

of this AD in accordance with Boeing Service 

Bulletin 747–21A2418, dated November 14, 

2002; Revision 1, dated October 16, 2003; 

Revision 2, dated March 4, 2004; or Revision 

3, dated December 21, 2004; are acceptable 

for compliance with the corresponding 

actions required by this AD. 

Alternative Methods of Compliance 

(AMOCs) 

(l)(1) The Manager, Seattle Aircraft 

Certification Office, FAA, has the authority to 

approve AMOCs for this AD, if requested in 

accordance with the procedures found in 14 

CFR 39.19. 

(2) Before using any AMOC approved in 

accordance with § 39.19 on any airplane to 

which the AMOC applies, notify the 

appropriate principal inspector in the FAA 

Flight Standards Certificate Holding District 

Office. 


sroberts on PROD1PC70 with PROPOSALS
56070 Federal Register / Vol. 71, No. 186 / Tuesday, September 26, 2006 / Proposed Rules 

Issued in Renton, Washington, on 

September 14, 2006. 

Kalene C. Yanamura, 

Acting Manager, Transport Airplane 

Directorate, Aircraft Certification Service. 

[FR Doc. 06–8232 Filed 9–25–06; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2006–25904; Directorate 

Identifier 2006–NM–077–AD] 

RIN 2120–AA64 

Airworthiness Directives; Bombardier 

Model DHC–8–100, –200, and –300 

Series Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), Department of 

Transportation (DOT). 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: The FAA proposes to 

supersede an existing airworthiness 

directive (AD) that applies to certain 

Bombardier Model DHC–8–100, –200, 

and –300 series airplanes. The existing 

AD currently requires modification of 

the flight compartment door; repetitive 

inspections for wear of the flight 

compartment door hinges following 

modification; and repair or replacement 

of the hinges with new hinges if 

necessary. This proposed AD would 

require using revised procedures for 

modifying and inspecting the flight 

compartment door and would reduce 

the applicability of the existing AD. 

This proposed AD results from a 

determination that certain cockpit doors 

are no longer subject to the existing 

requirements. We are proposing this AD 

to prevent failure of the alternate release 

mechanism of the flight compartment 

door, which could delay or impede the 

evacuation of the flightcrew during an 

emergency. This failure also could 

result in the flightcrew not being able to 

assist passengers in the event of an 

emergency. 

DATES: We must receive comments on 

this proposed AD by October 26, 2006. 

ADDRESSES: Use one of the following 

addresses to submit comments on this 

proposed AD. 

• DOT Docket Web site: Go to http:// 

dms.dot.gov and follow the instructions 

for sending your comments 

electronically. 

• Government-wide rulemaking Web 

site: Go to http://www.regulations.gov 

and follow the instructions for sending 

your comments electronically. 

• Mail: Docket Management Facility; 

U.S. Department of Transportation, 400 

Seventh Street, SW., Nassif Building, 

Room PL–401, Washington, DC 20590. 

• Fax: (202) 493–2251. 

• Hand Delivery: Room PL–401 on 

the plaza level of the Nassif Building, 

400 Seventh Street, SW., Washington, 

DC, between 9 a.m. and 5 p.m., Monday 

through Friday, except Federal holidays. 

Contact Bombardier, Inc., Bombardier 

Regional Aircraft Division, 123 Garratt 

Boulevard, Downsview, Ontario M3K 

1Y5, Canada, for service information 

identified in this proposed AD. 

FOR FURTHER INFORMATION CONTACT: Ezra 

Sasson, Aerospace Engineer, Systems 

and Flight Test Branch, ANE–172, FAA, 

New York Aircraft Certification Office, 

1600 Stewart Avenue, Suite 410, 

Westbury, New York 11590; telephone 

(516) 228–7320; fax (516) 794–5531. 

SUPPLEMENTARY INFORMATION: 

Comments Invited 

We invite you to submit any relevant 

written data, views, or arguments 

regarding this proposed AD. Send your 

comments to an address listed in the 

ADDRESSES section. Include the docket 

number ‘‘Docket No. FAA–2006–25904; 

Directorate Identifier 2006–NM–077–

AD’’ at the beginning of your comments. 

We specifically invite comments on the 

overall regulatory, economic, 

environmental, and energy aspects of 

the proposed AD. We will consider all 

comments received by the closing date 

and may amend the proposed AD in 

light of those comments. 

We will post all comments we 

receive, without change, to http:// 

dms.dot.gov, including any personal 

information you provide. We will also 

post a report summarizing each 

substantive verbal contact with FAA 

personnel concerning this proposed AD. 

Using the search function of that Web 

site, anyone can find and read the 

comments in any of our dockets, 

including the name of the individual 

who sent the comment (or signed the 

comment on behalf of an association, 

business, labor union, etc.). You may 

review the DOT’s complete Privacy Act 

Statement in the Federal Register 

published on April 11, 2000 (65 FR 

19477–78), or you may visit http:// 

dms.dot.gov. 

Examining the Docket 

You may examine the AD docket on 

the Internet at http://dms.dot.gov, or in 

person at the Docket Management 

Facility office between 9 a.m. and 5 

p.m., Monday through Friday, except 

Federal holidays. The Docket 

Management Facility office (telephone 

(800) 647–5227) is located on the plaza 

level of the Nassif Building at the DOT 

street address stated in the ADDRESSES

section. Comments will be available in 

the AD docket shortly after the Docket 

Management System receives them. 

Discussion 

On March 30, 1999, we issued AD 99–

08–04, amendment 39–11109 (64 FR 

16803, April 7, 1999), for certain 

Bombardier Model DHC–8–100, –200, 

and –300 series airplanes. That AD 

requires modification of the flight 

compartment door; repetitive 

inspections for wear of the flight 

compartment door hinges following 

modification; and repair or replacement 

of the hinges with new hinges, if 

necessary. That AD resulted from a 

report that the door lock mechanism of 

the flight compartment door jammed 

and could not be opened using the 

alternate release mechanism. We issued 

that AD to prevent failure of the 

alternate release mechanism of the flight 

compartment door, which could delay 

or impede the evacuation of the 

flightcrew during an emergency. This 

failure also could result in the 

flightcrew not being able to assist 

passengers in the event of an 

emergency. 

Actions Since Existing AD Was Issued 

Since we issued AD 99–08–04, 

various civil aviation authorities have 

mandated the installation of reinforced 

flight compartment doors, which 

negates the need for the modification 

required by paragraph (a) of the existing 

AD (Modification 8/2337) for airplanes 

on which the doors were installed in 

production. Modifications 8/2228, 8/ 

2229, 8/2231, 8/2232, 8Q100859, 

8Q900267, 8Q420101, 8Q420143, 

8Q200131, or 8Q420440 are equivalent 

to Modification 8/2337 (specified in 

paragraph (a) of the existing AD) for the 

flight compartment door alternate 

release mechanism. In addition, 

Bombardier has issued revised 

procedures for modifying and 

inspecting the flight compartment door. 

Relevant Service Information 

Bombardier has issued Service 

Bulletin 8–52–39, Revision ‘‘H,’’ dated 

September 9, 2004. Revision ‘‘H’’ is 

similar to Revision ‘‘D,’’ dated February 

27, 1998, which was cited in the 

existing AD as the appropriate source of 

service information for accomplishing 

the required actions. Among other 

things, Revision ‘‘H’’ revises the 

procedures used for modifying and 

inspecting the flight compartment door, 


sroberts on PROD1PC70 with PROPOSALS